ABSTRACT
This prospective study evaluated the role of cone beam computed tomography (CBCT) in the treatment of patients with impacted mandibular third molars at increased risk of inferior alveolar nerve (IAN) injury. Subjects with an increased risk of IAN injury, as diagnosed on panoramic radiographs, were enrolled in this study and underwent additional CBCT imaging. Two oral maxillofacial surgeons independently planned the surgical technique and estimated the risk of IAN injury on panoramic radiographs and on CBCT images. A test of symmetry and the McNemar test were executed to calculate the differences between the two imaging modalities. The study sample comprised 40 patients (mean age 27.6 years) presenting 53 mandibular third molars. Risk assessment for IAN injury based on panoramic radiography compared with CBCT imaging differed significantly (P<0.005). After reviewing the CBCT images, significantly more subjects were reclassified to a lower risk for IAN injury compared with the panoramic radiograph assessments. This change in risk assessment also resulted in a significantly different surgical approach (P<0.03). The results of this study show that CBCT contributes to optimal risk assessment and, as a consequence, to more adequate surgical planning, compared with panoramic radiography.
Subject(s)
Cone-Beam Computed Tomography/methods , Molar, Third/surgery , Patient Care Planning , Radiography, Panoramic/methods , Tooth Extraction , Tooth, Impacted/surgery , Adult , Decision Making , Female , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Intraoperative Complications/prevention & control , Male , Mandible/diagnostic imaging , Mandible/surgery , Mandibular Nerve/diagnostic imaging , Middle Aged , Molar, Third/diagnostic imaging , Osteotomy/methods , Pilot Projects , Prospective Studies , Radiography, Dental, Digital/methods , Risk Assessment , Tooth Crown/surgery , Tooth Root/diagnostic imaging , Tooth Root/surgery , Tooth, Impacted/diagnostic imaging , Trigeminal Nerve Injuries/prevention & control , Young AdultABSTRACT
The purpose of this study was to evaluate whether measurements on conventional cephalometric radiographs are comparable with 3D measurements on 3D models of human skulls, derived from cone beam CT (CBCT) data. A CBCT scan and a conventional cephalometric radiograph were made of 40 dry skulls. Standard cephalometric software was used to identify landmarks on both the 2D images and the 3D models. The same operator identified 17 landmarks on the cephalometric radiographs and on the 3D models. All images and 3D models were traced five times with a time-interval of 1 week and the mean value of repeated measurements was used for further statistical analysis. Distances and angles were calculated. Intra-observer reliability was good for all measurements. The reproducibility of the measurements on the conventional cephalometric radiographs was higher compared with the reproducibility of measurements on the 3D models. For a few measurements a clinically relevant difference between measurements on conventional cephalometric radiographs and 3D models was found. Measurements on conventional cephalometric radiographs can differ significantly from measurements on 3D models of the same skull. The authors recommend that 3D tracings for longitudinal research are not used in cases were there are only 2D records from the past.
Subject(s)
Cephalometry/methods , Cone-Beam Computed Tomography/methods , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Skull/diagnostic imaging , Cephalometry/statistics & numerical data , Chin/diagnostic imaging , Cone-Beam Computed Tomography/statistics & numerical data , Dental Occlusion , Humans , Image Processing, Computer-Assisted/statistics & numerical data , Imaging, Three-Dimensional/statistics & numerical data , Incisor/diagnostic imaging , Mandible/diagnostic imaging , Maxilla/diagnostic imaging , Nose/diagnostic imaging , Observer Variation , Palate/diagnostic imaging , Reproducibility of Results , Sella Turcica/diagnostic imaging , Software , Tooth Apex/diagnostic imagingABSTRACT
This study evaluated whether measurements on conventional frontal radiographs are comparable with measurements on cone beam computed tomography (CBCT)-constructed frontal cephalometric radiographs taken from dry human skulls. CBCT scans and conventional frontal cephalometric radiographs were made of 40 dry skulls. With I-Cat Vision((R)) software, a cephalometric radiograph was constructed from the CBCT scan. Standard cephalometric software was used to identify landmarks and calculate ratios and angles. The same operator identified 10 landmarks on both types of cephalometric radiographs on all Images 5 times with a time-interval of 1 week. Intra-observer reliability was acceptable for all measurements. The reproducibility of the measurements on the frontal radiographs obtained from the CBCT scans was higher than those on conventional frontal radiographs. There is a statistically significant and clinically relevant difference between measurements on conventional and constructed frontal radiographs. There is a clinically relevant difference between angular measurements performed on conventional frontal cephalometric radiographs, compared with measurements on frontal cephalometric radiographs constructed from CBCT scans, owing to different positioning of patients in both devices. Positioning of the patient in the CBCT device appears to be an important factor in cases where a 2D projection of the 3D scan is made.
